In order to prevent collisions with other aircraft, a variety of lights are mounted on the exterior of an aircraft in order to indicate its relative position to the other aircraft in the same general airspace. Such lighting systems include a rear (or aft) position lighting system, which typically includes a white light installed on the aft of an aircraft. The aircraft's lighting systems also include forward position lights, comprising a red light on the port wing and a green light on the starboard wing. Other aircraft operating in the vicinity of the lighted aircraft can discern the relative position and direction of travel of the lighted aircraft based on the color and movement of the rear and forward position lighting systems.
U.S. Federal Aviation Regulations (FARs) specify minimum and maximum light intensities for each of the rear and forward position lights, as a function of the angle of emission. The limitations for maximum intensities, known as “angular cut-offs,” are necessary to prevent excess overlap between these position lights so that other aircraft in the same general airspace can accurately discern between the individual position lights of an aircraft. This assists the other aircraft in determining the relative position of the lighted aircraft.
Traditionally, rear (as well as forward) position lighting systems have utilized incandescent lamps as light sources. These systems suffer from several disadvantages. Due to their principles of operation, incandescent lamps have a limited life compared to other light sources (e.g., fluorescent, solid-state, and high intensity discharge lights). The harsh environment under which an aircraft operates can further reduce the life of incandescent lamps. Since aviation safety regulations require that the aircraft's position lights be functioning when the aircraft is operating at night, the frequent failures of incandescent positioning lights may result in delayed flight departures as well as high maintenance costs due to replacement.
Some existing position lighting systems utilize light emitting diodes (LEDs). These lighting systems require clusters of LEDs on multiple printed circuit boards in order to meet the FAR requirements, thereby adding to their cost. Also, Rear Position Lights (RPLs) include masking on an outer lens in order to avoid light entering into overlap areas. This masking/coating sometimes gets peeled off, thus failing to meet the requirements with regard to angular range of illumination.
Other existing RPLs incorporate an overlap area baffle into the lens retainer or housing. These overlap baffles may be located on separate assemblies from the light-emitting diode (LED) module and LED printed circuit boards (PCBs). This means each new version of the RPL must have a new baffle designed even if it uses the same core LED lighting module.